Alechinsky from 1944 to 1948 followed a course in advertising, (book) illustration, typography and photography at the Ecole nationale supérieure des arts visual (ENSAV), formerly the Ecole nationale supérieure d'Architecture et des Arts Décoratifs (ENSAAD - La Cambre) (Cambre) in Brussels. He discovered in 1945 the work of Henri Michaux and Jean Dubuffet and developed a friendship with the art critic Jacques Putman, who dedicated several works to Alechinsky. In 1947 he started his painting career and he joined the Jeune Peinture Belge (including Louis Van Lint, Jan Cox and Marc Mendelson). That year he had his first solo exhibition in Brussels.
In 1949 he joined the Cobra group. Together with Christian Dotremont Alechinsky was the driving force behind the Belgian branch of Cobra. Together with the sculptors and Olivier Strebelle Reinhoud he was also the organizer of the community, "Les ateliers du Marais, which was a venue for many Cobra artists. He participated in both the Cobra Exhibitions in 1949 and 1951.
The latter, held in Liege, Alechinsky was even organized. He was in this period, so busy organizing various events and Cobra with the editors of the Journal of the Cobra movement, which he produced very little. Its production was only really started after the collapse of Cobra.
In 1951 went to Paris to Alechinsky with Stanley William Hayter at Atelier 17 'to study the art of engraving. Leaned over his work from 1951 to expressionism, whose previous had been mainly influenced by Surrealism. In Paris he became acquainted with artists like Alberto Giacometti, Bram van Velde and Asger Jorn. In 1954 he had his first exhibition in Paris in the gallery Nina Dausset. During the first half of the 50 years his work became increasingly abstract and one can freely turn in the outline view.
In 1954 Alechinsky in contact with the Chinese painting by the Chinese painter Ting Walasse, which would greatly influence his work. Besides the Chinese was also a significant influence of Japanese art. In addition, he also began to show an interest in oriental calligraphy. This is clear from the documentary film "Calligraphie japonaise" which he runs in 1955 at Kyoto. Since 1952 he also maintained a correspondence with all the Japanese calligrapher Shiryu Morita. In this way Alechinsky trying to bridge the gap between Eastern and Western art.
His international fame grew steadily. Alechinsky had his first major exhibition at the Museum of Fine Arts in Brussels in 1955. He also had exhibitions in London (1958), at the Kunsthalle Bern (1959), at the Venice Biennale in 1960 in the Belgian pavilion, in Pittsburgh and at the Stedelijk Museum in Amsterdam in 1961, in New York and the Danish Silkeborg (1963). From the sixties until today were all over the world to many exhibitions devoted Alechinsky's work. In 2000 it was in Ostend PMMK him with a retrospective.
In 1963 he moved his studio to Bougival, near Paris, where Andre Breton came to visit him. In 1965 he took part in the last great Surrealist exhibition in Paris Absolu L'Ecart in the Galerie d'Oeil. In 1977 was awarded the Andrew W. Alechinsky Mellon Award for his part in modern art. In 1983 he became professor of painting at the Ecole des Beaux Arts in Paris.
In 1994 he received an honorary doctorate from the Vrije Universiteit Brussel. One of his designs in 1995 for a Belgian stamp.
On the occasion of his eightieth birthday in 2007, the Royal Museums of Fine Arts of Belgium in Brussels tribute to him through a retrospective of his 60-year career.
Alechinsky also worked as a writer. Thus, his papers printed in the other hand, in a translation by Hugo Claus, Freddy De Vree.